[Oilpan] Create UnsafePtr to store on-heap pointers in Vector

third_party/WebKit/Source/platform/heap/Heap.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 #include "platform/heap/HeapPage.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/heap/Visitor.h"
 #include "wtf/AddressSanitizer.h"
 #include "wtf/Assertions.h"
 #include "wtf/Atomics.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
+template<typename T> class Member;
+template<typename T> class WeakMember;
+template<typename T> class UntracedMember;
+
 template<typename T, bool = NeedsAdjustAndMark<T>::value> class ObjectAliveTrait;
 
 template<typename T>
 class ObjectAliveTrait<T, false> {
 public:
     static bool isHeapObjectAlive(T* object)
     {
         static_assert(sizeof(T), "T must be fully defined");
         return HeapObjectHeader::fromPayload(object)->isMarked();
     }
@@ skipping 37 matching lines @@
     static inline bool isHeapObjectAlive(const Member<T>& member)
     {
         return isHeapObjectAlive(member.get());
     }
     template<typename T>
     static inline bool isHeapObjectAlive(const WeakMember<T>& member)
     {
         return isHeapObjectAlive(member.get());
     }
     template<typename T>
+    static inline bool isHeapObjectAlive(const UntracedMember<T>& member)
+    {
+        return isHeapObjectAlive(member.get());
+    }
+    template<typename T>
     static inline bool isHeapObjectAlive(const RawPtr<T>& ptr)
     {
         return isHeapObjectAlive(ptr.get());
     }
 
     // Is the finalizable GC object still alive, but slated for lazy sweeping?
     // If a lazy sweep is in progress, returns true if the object was found
     // to be not reachable during the marking phase, but it has yet to be swept
     // and finalized. The predicate returns false in all other cases.
     //
@@ skipping 395 matching lines @@
 void VisitorHelper<Derived>::handleWeakCell(Visitor* self, void* object)
 {
     T** cell = reinterpret_cast<T**>(object);
     if (*cell && !ObjectAliveTrait<T>::isHeapObjectAlive(*cell))
         *cell = nullptr;
 }
 
 } // namespace blink
 
 #endif // Heap_h